The long-term objective of this project is to discover treatments for West Nile virus (WNV) when administered after the virus has infected the central nervous system (CMS) and after the development of neurological sequelae, since no known therapy is currently available. Rationale: We have identified two antiviral agents, in the prior 3 years, with the potential for treating WNV disease. To facilitate pre-clinical development of the drugs, we have employed electrophysiological measurements to identify rodents with persistent neuropathology after the acute phase of infection. We are now poised in this proposal to answer important basic questions about pathogenic mechanisms causing or reversing viral encephalitis and persistent neuropathology, and to discover effective therapies that are important for the objectives of the RMRCE. Specific Aims: 1. Improve the efficacy of E16 and T-705. A therapeutic antibody, E16, will be mutated to remove the interaction with a receptor that mediates IgG efflux out of the brain back into the blood. Additionally, a 20-mer rabies virus glycoprotein will be used to influx E16 across the blood brain barrier (BBB) into the CNS. The efficacy and ribophosphorylation of an active pyrazine analog, T-705, will be verified directly in neurons, after which it will be administered directly into the brain or by intrathecal administration of hamsters to directly test its efficacy in the CNS. 2. Identify in rodents the pathogenesis for the transition from acute viral encephalitis to persisting neuropathology. Clinicoelectrophysiological assays that measure the function of three anatomical areas of the CNS will be used to identify rodents with persistent neuropathology. Immunohistochemistry, body temperature, animal motion/activity, and functional motor tests will also be employed to make comparisons between the acute infection and persisting neuropathology. 3. Verify the pre-clinical efficacy of anti-WNV drugs in rodent models. Improved antiviral drugs will be investigated for efficacy against acute WNV encephalitis and persisting neuropathology. We expect that improved therapeutics will still be efficacious after delaying the initiation of treatment, and that treatments may be effective during persisting neuropathology. Neuroprotective agents, based on published mechanisms, will be evaluated in the persistent neuropathology model. Two companies will collaborate for clinical development of these therapies. This research project fits within the RMRCE Integrated Research Focus on Viral Therapeutics, and will interact directly with RP 3.2.